There is plenty other things zul "could have" predicted from the cause of the cataclsym. So why only naga? And as far as I remember nothing split open releasing them, vashjir was always there we got pulled into it.

The only rift I recall happening in vashjir was the naga forcing their way into the throne of the tides.

This puts Zandalar at the top of a list called 'places Queen Azshara is going to raise from the bottom of the ocean with Neptulon's power.'

Naga expansion. It's a comin'.

Yea shes got the king of the sea's power now. Having her in just a raid is an understatement at this point. Plus shes been background hinted for 2 expansions now, which follows the trend of how previous expansions were revealed.